New engine/old trans
05-20-2007, 07:12 PM
#1
Staging Lane
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New engine/old trans I will be having a L92 crate engine put in a 1974 Elky. The wiring harness, as far as I know, does not come with the crate engine. I have a Turbo350 trans in the car now. I really wanted to avoid the expense of going with the OD trans because of computers & stuff. Well, I will have to buy a new special made harness anyway, so maybe it wont cost too much more for the OD, not counting the trans cost itself. I know the advantages of the OD trans, but I am on Soc Sec and this is the first time in my life I have REALLY spurged, so want to keep down the cost. Any thoughts on what trans to go with? JB
05-20-2007, 07:41 PM
#2
With my new 408 stroker I'm going with the race ready turbo 350 that is already in the car.
However in your case...
-What do you plan to do with the car?
-Do you plan on doing a lot of driving/cruising?
-Is the turbo 350 fresh or the stock transmission?
The OD trans will cost more in the end, but I believe is a better choice for a daily driver/long range cruiser. Unless mid-teens mpg sounds fun nowadays with the price of gas.
-Just make sure that whatever trans you end up with is up to the task.
Enjoy your L92 Elky.
However in your case...
-What do you plan to do with the car?
-Do you plan on doing a lot of driving/cruising?
-Is the turbo 350 fresh or the stock transmission?
The OD trans will cost more in the end, but I believe is a better choice for a daily driver/long range cruiser. Unless mid-teens mpg sounds fun nowadays with the price of gas.
-Just make sure that whatever trans you end up with is up to the task.
Enjoy your L92 Elky.
05-20-2007, 09:23 PM
#4
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I had planned on geting a tricked up T350 from TCI or one of the many others. I liked the Rapter trans from Transmisson Center. It has a MAACO special in it now. This is strictly a cruiser and will only see about 2,000 miles a year, so 15 MPG wont hurt too bad. Of course if I see a fartcan beside me, no telling what will happen. I will take it to the strip only to see what it will do for my own curiousity. JB
05-21-2007, 04:29 AM
#5
The TH350 may not have an overdrive gear, but is a more mechanically efficient transmission with a better spread of gear ratios for what it has. If only the add on overdrive units were more affordable.
For me the upgraded T350 was the transmission was the the cheaper choice. If I was to go with a overdrive trans I would swap to a five or six speed manual (I miss my Z).
Now with that said the 4l60E/65 would allow you to add cool stuff like paddle shifters and run a slightly less aggressive rear due to the 3:1 first gear. How about one of those, hopefully soon to be more common, six speed autos from GM?
For me the upgraded T350 was the transmission was the the cheaper choice. If I was to go with a overdrive trans I would swap to a five or six speed manual (I miss my Z).
Now with that said the 4l60E/65 would allow you to add cool stuff like paddle shifters and run a slightly less aggressive rear due to the 3:1 first gear. How about one of those, hopefully soon to be more common, six speed autos from GM?
05-22-2007, 08:32 AM
#6
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You need to do a bit more digging....
What rear gears are in the El Camino?
What tire size?
Depending upon how tall the tire and how steep the gears are, many OD trans may not work for your application without swapping rear gears too (yet another budget buster).
Here's an example: I've got a '78 El Camino (1st year of the last body style) with 2.41 rear gears in it and a TH350. I've thought seriously about going to a 700R4, but in order to do so, I'd HAVE to change rear gears, because 4th gear would be completely useless below 100mph otherwise.
Another point to ponder: The 4L60E isn't known for being bulletproof. They've got aluminum parts in the power-flow-path, which is bad. The shifting method they use is really rough on parts (try grabbing something spinning at engine speed and bringing it to a dead stop in half the shift time and have it not be hard on parts).
The TH350 and TH400 are far superior to the 700R4 / 4L60E / 65E / 70E in terms of strength. THe 4L80E is a derivative of the TH400 and is capable of big power, but is pricey and requires computer control (which the L92 computer can do). The 6L80E (and 90E) six speed autos are not available to speak of (dealer & a few salvage yards, but $$$), but should be able to be driven by the L92 computer.
'JustDreamin'
What rear gears are in the El Camino?
What tire size?
Depending upon how tall the tire and how steep the gears are, many OD trans may not work for your application without swapping rear gears too (yet another budget buster).
Here's an example: I've got a '78 El Camino (1st year of the last body style) with 2.41 rear gears in it and a TH350. I've thought seriously about going to a 700R4, but in order to do so, I'd HAVE to change rear gears, because 4th gear would be completely useless below 100mph otherwise.
Another point to ponder: The 4L60E isn't known for being bulletproof. They've got aluminum parts in the power-flow-path, which is bad. The shifting method they use is really rough on parts (try grabbing something spinning at engine speed and bringing it to a dead stop in half the shift time and have it not be hard on parts).
The TH350 and TH400 are far superior to the 700R4 / 4L60E / 65E / 70E in terms of strength. THe 4L80E is a derivative of the TH400 and is capable of big power, but is pricey and requires computer control (which the L92 computer can do). The 6L80E (and 90E) six speed autos are not available to speak of (dealer & a few salvage yards, but $$$), but should be able to be driven by the L92 computer.
'JustDreamin'
05-22-2007, 09:16 AM
#7
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You can get a great low mileage 4L80E from a junkyard for a good price. I got a 1400 mile 04 4L80E from a 2wd 2500HD with the harness and flexplate for $1000 delivered to my house. After rebuilding the 4L60E's in my caprice and impala, I didn't want to use one behind an engine with even more horsepower. It fits in my 78 trans am without any hammering on the trans tunnel. You'll have to reprogram your computer for the swap anyway. It won't cost anymore to program your computer to control the 4L80E. I know I am giving up some horsepower with a bigger trans but this is offset by the cost of rebuilding a 4L60E. I'm using 3.42 gears and will turn 2300 rpm's at 70 mph.
